Octupole deformation in light actinides within an analytic quadrupole octupole axially symmetric model with a Davidson potential

Abstract

The analytic quadrupole octupole axially symmetric model, which had successfully predicted Ra-226 and Th-226 as lying at the border between the regions of octupole deformation and octupole vibrations in the light actinides using an infinite well potential (AQOA-IW), is made applicable to a wider region of nuclei exhibiting octupole deformation, through the use of a Davidson potential, beta(2) + beta(4)(0)/beta(2) (AQOA-D). Analytic expressions for energy spectra and B(E1), B(E2), B(E3) transition rates are derived. The spectra of Ra222-226 and Th-224,Th-226 are described in terms of the two parameters phi(0) (expressing the relative amount of octupole vs quadrupole deformation) and beta(0) (the position of the minimum of the Davidson potential), while the recently determined B(EL) transition rates of Ra-224, presenting stable octupole deformation, are successfully reproduced. A procedure for gradually determining the parameters appearing in the B(EL) transitions from a minimum set of data, thus increasing the predictive power of the model, is outlined.